pH对水热法制备碳点产率的影响
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摘要
为探索水热法制备高产率碳点(CDs),以柠檬酸(CA)和乙二胺(EDA)混合水溶液为研究体系,基于物料分布系数计算研究反应溶液pH对CDs产率的影响。采用紫外-可见吸收光谱(UV-Vis)、荧光发射光谱(PL)、质谱(MS)等手段表征CDs的荧光性能。结果表明:基于溶液中物料分布系数计算,获得CDs产率最大时的溶液pH为5.5,并于该pH条件下制备了产率最高且荧光量子效率(QY)高达73.1%的CDs。基于分布系数计算预测CDs最大产率的方法同样可用于CA与其他胺类体系CDs的水热法制备。
In order to prepare the high yield carbon dots(CDs) by hydrothermal method, the effect of pH value of reaction solution on the yield of CDs was investigated based on the distribution coefficient calculation of various species in the mixed aqueous solution of citric acid(CA) and ethylenediamine(EDA). The fluorescence properties of the obtained CDs were characterized by UV-visible absorption spectra(UV-Vis), fluorescence emission spectroscopy(PL) and mass spectrometry(MS). Results showed that the pH value of maximum yield obtained by the calculation of distribution coefficient was 5.5, and at such a pH value, the CDs with the highest yield and fluorescence quantum efficiency(QY) of 73.1% was obtained. The method of predicting the maximum yield of CDs based on the distribution coefficient calculation could also be used for hydrothermal synthesis of CDs with CA and other amine systems.
In order to prepare the high yield carbon dots(CDs) by hydrothermal method, the effect of pH value of reaction solution on the yield of CDs was investigated based on the distribution coefficient calculation of various species in the mixed aqueous solution of citric acid(CA) and ethylenediamine(EDA). The fluorescence properties of the obtained CDs were characterized by UV-visible absorption spectra(UV-Vis), fluorescence emission spectroscopy(PL) and mass spectrometry(MS). Results showed that the pH value of maximum yield obtained by the calculation of distribution coefficient was 5.5, and at such a pH value, the CDs with the highest yield and fluorescence quantum efficiency(QY) of 73.1% was obtained. The method of predicting the maximum yield of CDs based on the distribution coefficient calculation could also be used for hydrothermal synthesis of CDs with CA and other amine systems.
引文
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[3] GE J,JIA Q N,LIU W M,et al.Red-emissive carbon dots for fluorescent,photoacoustic,and thermal theranostics in living mice [J].Advanced Materials,2015,27(28):4169.
[4] QU D,ZHENG M,ZHANG L G,et al.Formation mechanism and optimization of highly luminescent N-doped graphene quantum dots [J].Scientific Reports,2014,4(9):5924.
[5] SCHNEIDER J,RECKMEIER C J,XIONG Y,et al.Molecular fluorescence in citric acid-based carbon dots [J].Journal of Physical Chemistry C,2017,121(3):2014.
[6] SONG Y B,ZHU S J,ZHANG S T,et al.Investigation from chemical structure to photoluminescent mechanism:a type of carbon dots from the pyrolysis of citric acid and an amine [J].Journal of Materials Chemistry C,2015,3:5976.
[7] LIU H Z,ZHAO X,WANG F,et al.High-efficient excitation-independent blue luminescent carbon dots [J].Nanoscale Research Letters,2017,12(1):399.
[8] HU Q,PAAU M C,CHOI M F,et al.Better under standing of carbon nanoparticles via high-performance liquid chromatography-fluorescence detection and mass spectrometry [J].Electrophoresis,2014,35(17),2454.
[9] ZHU S J,ZHAO X H,SONG Y B,et al.Beyond bottom-upcarbonnanodots:citric-acid derived organic molecules [J].Nano Today,2016,11(2):128.
[10] SONG Y B,ZHOU S J,XIANG S Y,et al.Investiga tion into the fluorescence quenching behaviors and applications of carbon dots [J].Nanoscale,2014,6(9):4676.
[11] CHOUDHURY S D,CHETHODIL J M,GHARAT P M,et al.pH-elicited luminescence functionalities of carbon dots:mechanistic insights [J].Journal of Physical Chemistry Letters,2017,8(7):1389.
[12] ZHENG C,AN X Q,GONG J.Novel pH sensitive N-doped carbon dots with both long fluorescence lifetime and high quantum yield [J].RSC Advances,2015,5(41):32319.
[13] WANG C X,XU Z Z,CHENG H,et al.A hydrothermal route to water-stable luminescent carbon dots as nanosensors for pH and temperature [J].Carbon,2015,82(2):87.
[14] 李发美.分析化学[M].北京:人民卫生出版社,2007:40.